A theoretical model developed by the principal investigator demonstrates two intercalation sites in DNA for a tetramer duplex section extracted from the B-DNA structure. Using this model, a series of carcinogenic agents will be examined to assess reasons for their biological activity. Intercalation as well as binding to the backbone in the major or minor grooves will be considered as a step in the mode of action followed by the possibility of a covalent interaction within the complex formed by intercalation or by binding on the backbone. The binding energies will be calculated to determine the optimum binding configurations from which the possibility of formation of covalent bonds may be assessed. Trends in relative orientation of carcinogenic and carcinostatic compounds will be correlated to activity. The calculation of binding configurations will be performed with an IBM 3033 Computer but initial estimates and the final presentation will be made with the assistance of computer graphics techniques.